The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the internet of things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The internet of everything (IoE), which is a combination of the IoT technology and the big data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a machine-to-machine (M2M) communication, machine type communication (MTC), and so forth have been recently researched.
Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing information technology (IT) and various industrial applications.
Mobile terminals such as a mobile phone, a personal digital assistant (PDA) and the like are driven with rechargeable batteries due to their nature, and the battery of the mobile terminal is charged through supplied electronic energy by using a separate charging apparatus. In general, separate contact terminals are arranged outside of the charging apparatus and the battery, and the charging apparatus and the battery are electrically connected to each other through contact between the contact terminals.
However, since the contact terminal of each of the charging apparatus and the battery is outwardly protruded in such a contact type charging scheme, the contact terminal is easily contaminated by a rogue object and thus the battery charging is not correctly performed. Further, the battery charging may also not be correctly performed in a case where the contact terminal is exposed to moisture.
Recently, various charging schemes such as a wireless charging scheme, a non-contact charging scheme, and the like have been developed and used for electronic devices to prevent abnormal charging in the contact type charging scheme.
Such a wireless charging scheme is based on wireless power transmission/reception, and corresponds to, for example, a system in which a battery can be automatically charged if the battery is laid on a charging pad without the need of a connection between the mobile phone and a separate charging connector. In general, the wireless charging scheme is known to be found in wireless electrical toothbrushes or wireless electric shavers. Accordingly, a waterproof function can be improved since electronic products are wirelessly charged through the wireless charging scheme, and the portability of electronic devices can be increased since there is no need to provide a wired charging apparatus. Therefore, schemes related to the wireless charging scheme are expected to be significantly developed in the coming age of electric cars.
The wireless charging scheme largely includes an electromagnetic induction scheme using a coil, a resonance scheme using a resonance, and a radio frequency (RF)/microwave radiation scheme converting electrical energy to a microwave and then transmitting the microwave.
Up to now, the electromagnetic induction scheme is considered mainstream, but it is expected that the day will come when all electronic products are wirelessly charged, anytime and anywhere, without a wire in the near future. The expectation is strengthened due to recent successful experiments that wirelessly transmitted power to a destination spaced away by dozens of meters through the use of microwaves at home and abroad.
The electromagnetic induction scheme transmits electric power between a primary coil and a secondary coil. When a magnet is moved in a coil, an induction current occurs. By using the induction current, a magnetic field is generated at a transferring end, and electric current is induced according to a change of the magnetic field so as to make energy at a reception end. The phenomenon is referred to as magnetic induction, and the electromagnetic induction scheme using magnetic induction has high energy transmission efficiency.
With respect to the resonance scheme, Prof. Soljacic of Massachusetts Institute of Technology (MIT) announced a system in which electricity is wirelessly transferred using an electric power transmission principle of the resonance scheme based on a coupled mode theory to allow a device to be charged even when the device is separated from a charging device by several meters (m). The MIT team's wireless charging system employs resonance, which is the tendency for a tuning fork to oscillate at a particular frequency causing a wine glass next to the tuning fork to oscillate at the same frequency. The research team makes an electromagnetic wave containing resonating electrical energy instead of making resonating sounds. The resonating electrical energy is directly transferred only when there is a device having a resonance frequency and having parts of electrical energy which are not used and instead are reabsorbed into an electromagnetic field. Since the electrical energy is reabsorbed into an electromagnetic field instead of spreading in the air, unlike other electromagnetic waves, the electrical energy does not affect surrounding devices or people.
Meanwhile, a power receiving unit (PRU) wirelessly receives power from a PTU. In order to normally receive the power from the PTU, the PTU needs to exist within a range that it is possible to perform a wireless charging operation with the PTU. So, in order for the PRU to exist within the range that it is possible to perform the wireless charging operation with the PTU, the PTU needs to detect information regarding whether the PTU exists.
However, in wireless charging schemes which have been proposed up to now, a PTU does not inform a location of the PTU, so a PRU may not detect whether the PTU exists.
For example, a PRU may be a mobile station, and a PTU may be a wireless charging apparatus. Generally, the wireless charging apparatus is located at the interior or exterior of a building, and does not transmit information indicating that the wireless charging apparatus exists. So, a user of the mobile station does not discover the wireless charging apparatus, and the user suffers the inconvenience of wandering in or out of the building in order to discover the location of the wireless charging apparatus. Thus, the user of the mobile station may not discover the wireless charging apparatus at all. In this case, the user of the mobile station may not get to charge a battery of the mobile station.
So, there is a need for a scheme to transmit/receive PTU presence information in a wireless charging network.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.